I have a very old spare PC (built in 2010, i5 2500k, Nvidia GTX560Ti, 8GB RAM), the thing is so old the GPU does not support Vulkan (but does support DX11), it struggles with basic multitasking and eats through its RAM, even on Linux. Well guess what, LFS runs fine even on that hardware (at least in single player with 20 AI, I never tried multiplayer on that PC). Even a 500€ laptop you can buy today would run better, we can't cling to obsolete hardware and expect software to not take advantage of more recent technology.
If your PC is old but supports DX11, I would even expect performance to be better on the new LFS graphics, or at least very similar, as multi-threading means the CPU should use more cores and not be limited by single-core speed; yes the GPU will be working more, but DX11 optimisations over DX9 should help, so unless you're already GPU-bound, you shouldn't see a significant drop in FPS.
And to add to gu3st's point: I built my current PC in January 2023, it is pretty beefy, and yes, LFS runs better on the CPU's integrated GPU than it does on my very old PC.